1. Field of the Invention
This invention relates generally to an artificial illumination control system for photographic apparatus and, more particularly, to an artificial illumination control system for use with either ordinary flash lamps or other sources of artificial illumination such as a quench strobe.
2. Description of the Prior Art
Electronic photographic strobe devices of the type in which the flashlight produced by the flash tube of the device is automatically terminated after a predetermined quantity of light has been received from the scene being photographed by a light-responsive control portion of the device are well known in the art. Such strobes are commonly referred to as quench strobes. In addition to having an independent light-responsive control circuit in the strobe, it is also well known to utilize the exposure control circuit associated with the actual camera apparatus to control the firing and quenching of a strobe unit as is more fully disclosed in U.S. Pat. No. 3,776,112, by Wilwerding issued 1973. Wilwerding discloses a circuit coupled to the light-integrating exposure control circuit of a camera to effect the flash quenching of an electronic flash unit. Thus, it is well known to couple an electronically controlled shutter camera with a quenchable electronic strobe unit so that the strobe unit is quenched simultaneously with the command signal to return the shutter blade elements to their closed position.
Such an arrangement however would not be compatible with an exposure control system of the type described in a copending application for U.S. Pat. appln. Ser. No. 619,384 entitled "Exposure Control System With Fill-Flash Race Condition" by Edwin K. Shenk, filed Sept. 30, 1975. The aforementioned exposure control system is utilized in conjunction with a shutter blade arrangement of the so-called "scanning type" which embodies a pair of shutter blade elements, each of which includes a primary aperture therethrough to cooperatively define a gradually varying effective aperture size as a function of the position of the shutter blade elements. Each shutter blade element additionally includes a photocell sweep secondary aperture which apertures also cooperatively define a gradually varying effective secondary aperture in front of the exposure control photocell as a function of blade position. The photocell sweep secondary apertures are generally configured to progressively open ahead of the primary aperture so that the exposure control circuit effects the closing of the shutter blade elements at a time prior to which the film is fully exposed. Prematurely signalling the shutter blade elements to close prior to the time required for a full film exposure anticipates for the additional scene light which will impinge upon the film during the finite time required for the shutter blade elements to fully close. Thus, quenching the strobe solely as a function of the exposure control system command signal to initiate closing of the shutter blade elements as disclosed in U.S. Pat. No. 3,776,112, supra will result in an under-exposure since the strobe is quenched almost instantaneously.
Thus, it is a primary object of this invention to provide an exposure control system which is compatible for use with both an ordinary flash lamp and a quench strobe.
It is also an object of the invention to provide a quench strobe wherein the quench signal is delayed by a predetermined time.
It is a further object of this invention to provide a time delay means which may be utilized in conjunction with a quench strobe so that the quench strobe can be used interchangeably with an ordinary flash lamp.
It is an even further object of this invention to provide time delay means for use with photographic apparatus of the type having scanning shutter blade elements with primary apertures and secondary photocell apertures whereby the time delay of the time delay means is correlated to the anticipation characteristic of the photocell secondary apertures to accommodate for a quench strobe in which the artificial light output may be almost instantaneously terminated.
Other objects of the invention will in part be obvious and will in part appear hereinafter. The invention accordingly comprises the mechanism and system possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure.